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A questionnaire covering management practices and producer perception of the effects of gastrointestinal nematode infections was sent to dairy and beef producers in the northeastern US. The mailing list was derived from membership in grazing groups and attendance at grazing events. A final total of 474 responses were suitable for analyses. These responses covered 14 states, but for the purpose of analysis were broken into five groups: New England (NE), Vermont (VT), New York (NY), Pennsylvania (PA), and south and west (S and W) of Pennsylvania. Two-thirds of the responses were from dairy producers. The average number of animals for the farms was 50 cows, 27 heifers, and 20 calves. The average acreage used for grazing was 70 acres, and about two-thirds of the responses used rotational grazing for at least the cows. About one-half of the rotational grazers had been practicing rotational grazing for more than 5 years. Most rotational programs for cows involved a daily rotation, but the rotational interval for other age groups was longer. There was a difference of about 2 months (5.25-7.27) in the length of the grazing season as one moved from New England to south and west of Pennsylvania. Parasite control practices varied greatly by location and animal class. Most producers used anthelmintics one to two times per year, but 10-30% of responses said they did not deworm their cattle. The most common time to deworm was in the spring, and the second most common time was the fall. Between 10 and 20% of respondents reported deworming as a response to decreased productivity or body condition. The use of anthelmintics increased as the location moved from New England to south and west of Pennsylvania. Producer perception of parasite effects was closely related to their anthelmintic use, and also increased as the location moved to the south, and is most likely the result of the increased length of the grazing season. Of producers who ascribed estimated a cost of the parasite, the majority estimated this cost to be between US$ 5 and 20 per animal per year. 相似文献
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A three-year study was conducted to measure the effects of varying levels of dairy slurry application on mineral concentration of forages from three soils types. Slurry was applied to orchardgrass (Dactylis glomerata [L.] cv. Pennlate) growing in 60-cm diameter drainage lysimeters to measure the effect of four levels of slurry (urine and feces) N application (0, 168, 336, and 672 kg of N.ha-1.yr-1) on mineral (P, K, Ca, Mg) concentration of the forage on three soil types (Hagerstown, Hartleton, and Rayne). The results were then related to potential effects on performance and health of grazing ruminants. Forage P was not affected by slurry application (mean = 0.46% of DM). Forage grown on the Hartleton soil had the highest (P < 0.05) P concentration (0.6% of DM). Forage K increased (P < 0.05) with increased slurry (2.50, 2.85, 3.22, and 3.45% of DM, respectively), and was lowest (P < 0.05) for forage grown on the Rayne soil (2.69% of DM). Forage Ca decreased (P < 0.05) with increased slurry (0.59, 0.56, 0.50, and 0.49% of DM, respectively) and was not affected by soil type. Forage Mg also decreased (P < 0.05) with increased slurry (0.25, 0.24, 0.24, and 0.23% of DM, respectively), and was highest (P < 0.05) for the Hartleton soil (0.27% of DM). The variable results in mineral concentration associated with soil type may have, in part, been due to prior soil fertility. The P and Mg concentrations in all treatments were generally adequate for grazing ruminants. The K concentrations were high in relation to NRC recommendations for prepartum dairy cows, which might predispose them to milk fever. The Ca concentrations were inadequate for lactating dairy cows. Comprehensive forage testing and diet formulation based on individual farm situations is the best strategy to ensure proper mineral nutrition of grazing animals. 相似文献
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Darryl G. Stout 《Journal of Agronomy and Crop Science》1998,181(4):263-266
Experiments were conducted to determine if diurnal temperature variation could be used to prime cicer milkvetch ( Astragalus cicer L.) seed and thereby shorten the time for seed germination. For untreated cicer miikvetch seed at constant 20°C, 50% of the seeds germinated in 8.2 days and 90% of the seeds germinated in 10.5 days. In contrast, seed that was first primed for 7 days with a diurnal temperature variation (35 (8h)/5 (16h) °C) had values of 1.9 days and 3.3 days, respectively. A second experiment evaluated priming of seed in bulk to test if a procedure might be developed that could be scaled up to prime commercial quantities of seed. A bulk sample of seed was soaked in water for 5h at room temperature and then kept in a high humidity atmosphere during 7 days of priming at 35/5°C. Hydrated seed from the bulk sample had 50% germination in 2.7 days and 90% germination in 5.3 days. When the bulk sample was dried for 8 days at room temperature, the benefit of priming on shortening germination time was retained. It is likely that diurnal temperature priming could be adapted to large volumes of seed. 相似文献
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Exotic plant invasions threaten ecological communities world-wide. Some species are limited by a lack of suitable pollinators, but the introduction of exotic pollinators can facilitate rapid spread. In Tasmania, where many non-native plants are naturalised, exotic honeybees (Apis mellifera) and bumblebees (Bombus terrestris) have become established. We determined how these species affect the pollination of Lupinus arboreus, an invasive, nitrogen-fixing shrub, which is rarely visited by native pollinators. The proportion of flowers setting seed and the number of ovules fertilised per flower were positively related to the visitation rates of both exotic bee species. There was no effect of bee visitation rates on the proportion of seeds aborted prior to maturity, possibly due to post-fertilisation environmental constraints. We conclude that the spread of B. terrestris may not alter the fecundity of L. arboreus because of the pollination service provided by A. mellifera, and discuss potential interactions between these two bee species. 相似文献